I installed a swimming pool which I want to "buffer" from an ajoining park and
backyard neighbors. I have a 15' planting bed from the respective property
lines to the edge of what will be a 3' wood "boardwalk" along the pool's
coping.

I'd like to plant a wide variety of evergreen shrubs that will generally have
an upright habit. (More height than width) I don't want a "Hedge wall" of one
single, continuious variety.

If I pick shrubs which boast the like of: "Mature size 12' wide x 30' tall" and
"20' wide x 40' tall" but plant them closer together, will they grow tall to
fill their space, or will not allowing mature width via trimming somehow stunt
their mature height?

thanks